<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<style>
*{
    margin: 0;
    padding: 0;
    box-sizing: border-box;
}
.wrap{
    width: 1190px;
    height: 800px;
    margin: 0 auto;
    background-color: orange;
}
/* 辅助盒子，解决浮动换行问题：原理 width = mr+ml+width1
                                  1190 = -5+-5+1200  
因此扩展了子盒子box的宽度
*/
.box{
    margin:0 -5px;
}
li.item{
    float: left;
    list-style: none;
    margin: 0 5px;
    width: 230px;
    height: 330px;
    background-color: black;
    color:#fff;
}
</style>

<body>
    <div class="wrap">
        <div class="box">
            <ul>
                <li class="item">1</li>
                <li class="item">2</li>
                <li class="item">3</li>
                <li class="item">4</li>
                <li class="item">5</li>
            </ul>
        </div>
    </div>
</body>
<script></script>

</html>